What is Strontium and How Does It Work?
Strontium is a natural trace mineral, chemically similar to calcium, with about 99% of its content in the human body concentrated in the bones. It is found in soil, water, and various foods, with a typical diet providing a very small daily amount of 0.5–1.5 mg. In the context of dietary supplements and medications, strontium is used to support bone health, particularly in cases of osteoporosis. The mineral's action is thought to work in a unique 'dual action' way, both promoting bone formation and slowing down bone breakdown, a process that becomes unbalanced in osteoporosis.
The Critical Difference: Strontium Ranelate vs. Strontium Citrate
When considering the safety of daily strontium, the form you take is the most important factor. There is a significant distinction between the prescription drug, strontium ranelate, and the over-the-counter supplement, strontium citrate.
Strontium Ranelate (Prescription Drug) This is a specific, laboratory-made form of strontium combined with ranelic acid. It has been used in some countries, primarily in Europe, as a prescription treatment for severe osteoporosis. Extensive safety reviews have identified serious risks associated with daily use of strontium ranelate, including an increased risk of cardiovascular events like heart attacks, as well as venous thromboembolism (VTE), which are blood clots in the veins. Due to these risks, its use is heavily restricted in Europe and it is not approved for use by the U.S. Food and Drug Administration (FDA). Side effects can also include severe allergic reactions, headaches, and gastrointestinal upset.
Strontium Citrate (Dietary Supplement) This form combines strontium with citric acid and is widely available as an over-the-counter supplement. Manufacturers often promote it as a safe and effective alternative to the prescription drug. However, the scientific evidence regarding its long-term safety and efficacy is less conclusive and independent medical sources are more cautious. While generally better tolerated than strontium ranelate, some side effects like diarrhea, headaches, and rashes have been reported. Critically, there are also case reports linking strontium citrate to the serious allergic reaction DRESS syndrome, though it appears to be far less common than with strontium ranelate. Health Canada has also taken a precautionary approach, advising those with heart or circulatory problems against using strontium supplements, regardless of the form.
Who Should Avoid Strontium Daily?
For both forms of supplemental strontium, daily intake is not suitable for everyone. Certain individuals should avoid it entirely or use it with extreme caution after consulting a healthcare provider:
- Individuals with a history of heart disease, stroke, or uncontrolled high blood pressure.
- Those with a history of blood clots or who are immobile, as this increases clotting risk.
- People with severe or moderate kidney impairment, as strontium is eliminated through the kidneys and can accumulate to toxic levels.
- Pregnant or breastfeeding women, due to insufficient safety data.
- Individuals with Paget's disease, as it can affect bone metabolism.
Important Considerations for Strontium Absorption
For those who do take strontium citrate, proper timing is essential. Strontium and calcium compete for the same absorption pathways in the body. To maximize the absorption of strontium, you should take it at least two hours away from calcium-rich foods or calcium supplements. Taking strontium at night, on an empty stomach, is a common practice to ensure this separation.
The Need for Further Research
The lack of robust, independent, long-term studies on strontium citrate is a major concern. Much of the positive data on strontium for bone health is from studies on the more dangerous ranelate version, or from small, manufacturer-funded trials of citrate. Furthermore, strontium can cause an artefactual increase in bone mineral density (BMD) scans, as it is a denser element than calcium. This means that an increase on a DEXA scan might not fully reflect a true increase in bone strength, and healthcare providers need to interpret results carefully.
The Bottom Line
While naturally occurring strontium in foods is perfectly safe, taking a daily strontium supplement carries clear risks and significant unknowns depending on the specific form. Prescription strontium ranelate is widely known to be unsafe for many populations, and the safety of over-the-counter strontium citrate is not fully established by independent research. The decision to use a daily strontium supplement should only be made in consultation with a qualified healthcare professional who can weigh the potential benefits against your personal health risks, particularly related to cardiovascular and kidney function. For those seeking to improve bone health, other proven methods like adequate calcium and vitamin D intake, along with weight-bearing exercise, are typically the safer and more researched first line of defense.
Comparison of Strontium Forms
| Feature | Strontium Ranelate | Strontium Citrate |
|---|---|---|
| Source | Synthetic compound | Natural mineral salt |
| Availability | Prescription drug (Europe, restricted) | Over-the-counter supplement (US, Canada) |
| Cardiovascular Risk | Increased risk of heart attack, blood clots | Possible risk, warrants caution |
| Side Effects | Serious (DRESS syndrome, VTE), GI upset | Generally milder (GI upset, headache, rash), but severe reactions possible |
| Long-Term Safety | Not approved in US, restricted in Europe | Less robust independent data, requires more research |
| FDA/EMA Status | Not FDA-approved, restricted by EMA | No official regulation as supplement |
